Electronic structure of dilute alloys

Ge, Meng; Claessen, R.; Reinert, F.; Zimmermann, R.; Steiner, P.; Hüfner, S.

doi:10.1088/0953-8984/8/30/007

Cited by 5 publications

(3 citation statements)

References 27 publications

(63 reference statements)

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“…We apply this formalism to two alloys characterized by a large size mismatch between the constituents and a phase diagram with a large miscibility gap: Au-Ni and Ag-Cu. Au-Ni has received a lot of attention, both experimentally and theoretically, especially due to a specific behavior of the SRO in this system [12,18,[37][38][39][40][41][42][43][44][45]. Ag-Cu has also been frequently studied, both in the bulk and at interfaces [2,8,13,14,[46][47][48][49][50][51][52][53], and the two systems have been compared theoretically in a few studies [21,22,30,48].…”

Section: Introductionmentioning

confidence: 99%

Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys

2017

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We present a novel energetic model that takes into account atomistic relaxations to describe the thermodynamic properties of A c B 1−c binary alloys. It requires the calculation of the energies on each site of a random solid solution after relaxation as a function of both the local composition and the nominal concentration. These site energies are obtained by molecular static simulations using N-body interatomic potentials derived from the second-moment approximation (SMA) of the tight-binding scheme. This new model allows us to determine the effective pair interactions (EPIs) that drive the short-range order (SRO) and to analyze the relative role of the EPIs' contribution to the mixing enthalpy, with respect to the contribution due to the lattice mismatch between the constituents. We apply this formalism to Au-Ni and Ag-Cu alloys, both of them tending to phase separate in the bulk and exhibiting a large size mismatch. Rigid-lattice Monte Carlo (MC) simulations lead to phase diagrams that are in good agreement with both those obtained by off-lattice SMA-MC simulations and the experimental ones. While the phase diagrams of Au-Ni and Ag-Cu alloys are very similar, we show that phase separation is mainly driven by the elastic contribution for Au-Ni and by the EPIs' contribution for Ag-Cu. Furthermore, for Au-Ni, the analysis of the SRO shows an inversion between the tendency to order and the tendency to phase separate as a function of the concentration.

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Section: Introductionmentioning

confidence: 99%

Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys

2017

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“…Since the one-electron theory predicts a linewidth of no more than 0.05 Ryd for the Fe 3d spin-down and spin-up states, the incoherent part may be present in PE spectra. For Au-Ni alloys, a study using resonant photoemission spectroscopy (RESPES) confirmed the existence of the two-hole satellites within the Au host d band [27], which had been predicted on the grounds that the difference spectra between alloy and pure Au spectra has a peak which follows a similar photon energy dependence of the relative intensity [28].…”

Section: Discussionmentioning

confidence: 79%

Photoelectron spectroscopy study of Fe-diluted Au–Fe alloys

Nahm

Noh

Choi

et al. 2003

J. Phys.: Condens. Matter

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The electronic structure of Fe-diluted Au–Fe alloys has been studied by taking core-level and valence-band spectra using x-ray photoemission spectroscopy and synchrotron radiation. From the core-level spectroscopy, we found that the Fe 2p spectrum is composed of d6 and d7 multiplets from Fe impurity atoms. This behaviour is qualitatively discussed within the context of electron–electron interaction. In order to explore the electron-correlation effects in the valence band, we obtained Fe 3d partial spectral weights by taking advantage of the Cooper-minimum phenomenon of an Au 5d photoionization cross section. It was found that the spin-down states have an appreciable amount of spectral weights throughout the host Au 5d band, contrary to previous one-electron calculations predicting two-peak structure of the Fe 3d states. We suggest that this discrepancy results from the correlation effect of the Fe 3d electrons.

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“…Therefore, for many alloys, the loss (signified by ε 2 ) usually increases compared with their respective constituent metals. [ 63,64 ] However, as seen in the prior examples, ε 2 can be contained and suppressed through alloying in certain systems (e.g., Au–Ag, Au–Cu, and Mg–Al) fabricated under specific conditions. Furthermore, another broad class of alloys—the mixing of the coinage metals with other electron‐rich ones, may provide a promising pathway to achieve materials with low ε 2 .…”

Section: Optical Properties Of Metal Alloysmentioning

confidence: 96%

Emergent Opportunities with Metallic Alloys: From Material Design to Optical Devices

Gong

Lyu

Palm

et al. 2020

Advanced Optical Materials

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devices is the fact that their dielectric function (i.e., permittivity, ε = ε 1 + iε 2) is predefined. Thus, several research groups, including ours, have recently merged two almost orthogonal fields, photo nics, and metallurgy, to pursue metallic materials with arbitrary permit tivity. [1-5] Alloying is now a burgeoning framework for achieving materials with engineered optical properties, encom passing both nanostructures and thin films, as will be surveyed in this Review. Plasmonics exploits the interaction of incident electromagnetic fields with the col lective motion of free electrons (plasmons) in metals. This phenomenon confines the electromagnetic fields in close vicinity of the metal interfaces, dramatically enhancing the electrical field intensity surrounding the material. [6-8] Plasmons can be divided into two categories: surface plasmon polaritons (SPP) that propagate along the metal and dielectric interface, and localized surface plasmon resonance (LSPR) that are confined in a subwavelength nanostructure. For the latter, their optical scattering or absorp tion (and/or the nearby dielectrics and semiconductors) can be significantly increased. As a result, these enhancement effects are the underpinnings to a range of novel optical processes, and have found countless applications in photovoltaics, [9-11] photo catalysis, [12-14] bio and chemicalsensing, [15,16] electrooptical modu lation, [17,18] and superabsorbers. [19-21] As expected, the features of either type of plasmon are strongly dependent upon the dielectric function of the material, which is somewhat fixed in metals. Concerning materials, coinage metals, such as Au, Ag, or Cu, are widely used in photonics due to their abundant free electrons and chemical stability. [1] Other noble metals including Metallic nanostructures and thin films are fundamental building blocks for next-generation nanophotonics. Yet, the fixed permittivity of pure metals often imposes limitations on the materials employed and/or on device performance. Alternatively, metallic mixtures, or alloys, represent a promising pathway to tailor the optical and electrical properties of devices, enabling further control of the electromagnetic spectrum. In this Review, a survey of recent advances in photonics and plasmonics achieved using metal alloys is presented. An overview of the primary fabrication methods to obtain subwavelength alloyed nanostructures is provided, followed by an in-depth analysis of experimental and theoretical studies of their optical properties, including their correlation with band structure. The broad landscape of optical devices that can benefit from metallic materials with engineered permittivity is also discussed, spanning from superabsorbers and hydrogen sensors to photovoltaics and hot electron devices. This Review concludes with an outlook of potential research directions that would benefit from the on demand optical properties of metallic mixtures, leading to new optoelectronic materials and device opportunities.

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Electronic structure of dilute alloys

Cited by 5 publications

References 27 publications

Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys

Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys

Photoelectron spectroscopy study of Fe-diluted Au–Fe alloys

Emergent Opportunities with Metallic Alloys: From Material Design to Optical Devices

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